全文获取类型
收费全文 | 1555篇 |
免费 | 101篇 |
国内免费 | 221篇 |
专业分类
安全科学 | 358篇 |
废物处理 | 19篇 |
环保管理 | 305篇 |
综合类 | 613篇 |
基础理论 | 266篇 |
污染及防治 | 111篇 |
评价与监测 | 92篇 |
社会与环境 | 75篇 |
灾害及防治 | 38篇 |
出版年
2024年 | 4篇 |
2023年 | 20篇 |
2022年 | 23篇 |
2021年 | 40篇 |
2020年 | 56篇 |
2019年 | 44篇 |
2018年 | 40篇 |
2017年 | 48篇 |
2016年 | 63篇 |
2015年 | 49篇 |
2014年 | 76篇 |
2013年 | 120篇 |
2012年 | 112篇 |
2011年 | 122篇 |
2010年 | 85篇 |
2009年 | 90篇 |
2008年 | 67篇 |
2007年 | 122篇 |
2006年 | 123篇 |
2005年 | 89篇 |
2004年 | 69篇 |
2003年 | 65篇 |
2002年 | 47篇 |
2001年 | 40篇 |
2000年 | 37篇 |
1999年 | 29篇 |
1998年 | 24篇 |
1997年 | 23篇 |
1996年 | 34篇 |
1995年 | 28篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1877条查询结果,搜索用时 13 毫秒
131.
江苏阳澄湖螺类群落的空间分布格局 总被引:3,自引:0,他引:3
2008年1月~2009年10月对江苏阳澄湖螺类群落结构进行了季节调查研究。共采集到螺类4科5属6种,优势种为铜锈环棱螺,次优种为长角涵螺。阳澄湖螺类平均密度为220±47 ind./m2,平均生物量为2331±469 g/m2,螺类密度和生物量在年际和季节间均无明显差异,但群落结构存在显著的空间变化,密度在东湖区和中华绒螯蟹围网养殖区较大、西湖区最小,生物量围网养殖区最高、西湖区最低;铜锈环棱螺密度围网养殖区最高、西湖区最低,长角涵螺密度东湖区最高、围网养殖区次之、入湖河流及其它湖区极低。中华绒螯蟹养殖未导致围网养殖区螺类数量下降,螺类(主要是铜锈环棱螺)的投放可能是该区螺类密度、生物量及铜锈环棱螺所占比例较高的主要原因之一。逐步回归分析表明,水深是影响螺类群落整体密度和生物量空间分布差异的主要因子;典型对应分析(CCA)表明,铜锈环棱螺主要分布在叶绿素a较高的水域,而长角涵螺和纹沼螺则主要分布在透明度较大的地方 相似文献
132.
Quantitative methods have been applied to the study of floristic structure and diversity in Samarskaya Luka. The results show that Samarskaya Luka is a floristically heterogeneous area in which six elementary floras can be distinguished. This area has been assessed as a floristically autonomous formation, and its floristic representativeness was estimated. 相似文献
133.
生物菌剂对石油污染土壤生物修复作用的研究 总被引:4,自引:0,他引:4
在实验室条件下,研究了生物菌剂的投加量、投加方式及环境温度对石油污染土壤的修复作用 结果表明,土壤中石油烃的降解效果与生物菌剂的投加量呈正相关,当生物菌剂投加量为0.6mg·kg-1时,修复,48 d 后,石油烃的降解率为87%.GC-MS分析结果表明,石油污染原土中烷烃的含量最高为82.1%其次为烯烃,含量为16%,还含有少量的胡萝卜烷、烷基萘、甾烷和藿烷% 添加生物菌剂修复40 d 后,峰的数量由32个减少为14个,表明异构烷烃、烯烃、胡萝卜烷全部被降解,残留的物质为较难降解的正构烷烃、藿烷和甾烷,呈现前高后低的峰形,即接种细菌优先降解高碳组分,将长链的烷烃降解为短链的烷烃,随着生物菌剂投加量的增加,土壤中残留石油烃的含量逐渐降低% 一次加入生物菌剂修复,48 d后的峰高明显低于分2 次加入的相应值,故一次性全部加入生物菌剂是最佳的投加方式% 温度是限制石油污染土壤生物修复的重要环境因素,当温度为30℃第,48 d 的降解率可达80%,当温度为20℃,第,48 d的降解率可达60%,温度高有利于土壤中石油烃的降解,加快修复 相似文献
134.
Effect of sulfate on the methanogenic activity of a bacterial culture from a
brewery wastewater during glucose degradation 总被引:1,自引:1,他引:1
Nusara Sinbuathong Sutha Khaodhiar Winai Liengcharernsit Pramote Sirirote Daniel Watts 《环境科学学报(英文版)》2007,19(9):1025-1027
The maximum specific methanogenic activity (SMA) of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading basis. Batch experiments were conducted in serum bottles at pH 7 and 35℃. A comparison of the values indicates that the SMA of this mixed culture was increased and reached its highest level of 0.128 g CH4 gas COD/(g VSS.d) when biomass was in contact with sulfate at a ratio of 1:0.114 by weight. 相似文献
135.
136.
BAYESIAN MODELS OF FORECASTED TIME SERIES1 总被引:1,自引:0,他引:1
Roman Krzysztofowicz 《Journal of the American Water Resources Association》1985,21(5):805-814
Bayesian Processor of Forecasts (BPF) combines a prior distribution, which describes the natural uncertainty about the realization of a hydrologic process, with a likelihood function, which describes the uncertainty in categorical forecasts of that process, and outputs a posterior distribution of the process, conditional upon the forecasts. The posterior distribution provides a means of incorporating uncertain forecasts into optimal decision models. We present fundamentals of building BPF for time series. They include a general formulation, stochastic independence assumptions and their interpretation, computationally tractable models for forecasts of an independent process and a first-order Markov process, and parametric representations for normal-linear processes. An example is shown of an application to the annual time series of seasonal snowmelt runoff volume forecasts. 相似文献
137.
Wendy A. Rice Steven M. Gorelick 《Journal of the American Water Resources Association》1985,21(6):919-930
A graphical inverse method for determining the regional transmissivity distribution was applied to three field problems. The study areas were the Hanford Site, Washington; the Rocky Mountain Arsenal, Colorado; and the Nevada Test Site, Nevada. This method can aid in flow system conceptualization by revealing the location of bedrock controls for groundwater flow. It is a valuable tool for aiding the hydrogeologist in asking questions about the nature of trends in the pattern of transmissivity values. Quantitative estimates of regional transmissivities can be used as starting points for further parameter refinement. Sensitivity analysis using Monte Carlo simulation shows that quantitative estimates of transmissivity can be obtained when measurement error in the hydraulic head does not cause a large error in the hydraulic gradient. 相似文献
138.
Ute Dymon 《Environmental management》1987,11(6):775-792
Groundwater mapping is a critical component of efficient water resource management today. Difficulties arise when highly specialized and complex groundwater data are collected and presented in map form. This is an analysis of the map content and its presentation in the USGS Hydrological Investigation Atlas Series. This analysis reveals the problems to be surmounted in mapping groundwater information. The technical nature of the groundwater data requires special design considerations. 相似文献
139.
Methods used to determine adverse impacts of air pollution on four levels of biological organization of terrestrial ecosystems were evaluated for their use in decision making by federal land managers of class I areas and as guidelines for scientists employed to design field studies in these areas. At the level of the individual, visible injury, biomass, and sulfur uptake were the most often used components; at the population level, natality and mortality; at the community level, diversity; and at the ecosystem level, biogeochemical cycling. Most studies focused on structural responses of individual organisms. These components are relatively sensitive and are easy and inexpensive to measure; however, linkages of these parameters to adverse impacts on populations, communities, or ecosystems are lacking. Measurements of effects of air pollution at the higher levels of organization are confounded by natural variability, long response times, climatic variation, pathogens, and other factors. In addition, the lack of replication and of true control areas creates severe problems for design of monitoring programs and testing of hypotheses concerning effects. 相似文献
140.
朱爱虹 《中国环境管理干部学院学报》2002,12(2):76-78
以精神文明建设为先导落实育人目标,是贯彻高校教育方针的重要方面。本文从抓好队伍和校园文化建设为切入点,提出了拓宽育人渠道、改进育人方法和强化素质教育的建议。 相似文献